Step 1: Hardware Configuration - Analog Devices dBCool ADT7473 Manual

ADT7473
STEP 1: HARDWARE CONFIGUR
During system design, the motherboard sensing and control
capabilities should be addressed early
Decisions about how these capabilities are used should involve
the ystem thermal/mechanical engineer. Consider the s
follo wing questions:
1. What ADT7473 functionality will be used?
•
PWM2 or SMBALERT ?
•
TACH4 fan speed measurement or overtemperature
THERM function?
The ADT7473 offers multifunctional pins that can be
reconfigured to suit different system requirements and
physical layouts. These multifunction pins are software
programmable.
REMOTE 1 =
AMBIENT TEMP
LOCAL =
VRM TEMP
REMOTE 2 =
CPU TEMP
ATION
in the design stages.
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
Figure 45. Hardware Configuration Example
2. How many fans will be supported in the system, three or
four? This influences the choice of whether to us
TACH4 pin or to reconfigure it for the THERM function.
3. Is the CPU fan to be controlled using the ADT7473 or will
it run at full speed 100% of the time?
If run at full speed, 100% of the time, this frees up a PWM
output, but the system is louder.
4. Where will the ADT7473 be physically located in the
system?
This influen
measurement channels to particular sy
For example, locating the ADT7473 close to the VRM
controller circuitry allows the VRM temperature to be
monitored using the local temperature channel.
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 1
MEASUREMENT
PWM
MIN
RAMP
CONTROL
MUX
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 3
AND 4
MEASUREMENT
Rev. A | Page 34 of 76
ces the assignment of the t emperature
stem thermal zones.
PWM
CONFIG
PWM
PWM1
GENERATOR
TACH1
PWM
CPU FAN SINK
CONFIG
PWM
PWM2
GENERATOR
TACH2
PWM
CONFIG
FRONT CHASSIS
PWM
PWM3
GENERATOR
TACH3
REAR CHASSIS
e the